The importance of emotional support dog registry is to deliver a legitimate NSAR certificate along with photo attached identity proof for the help of the patients to manage the FHA policy, rental housing with no-pet policies, landlord compulsion, and to take the ESA along with him/her for air travels.
Those who own such certificate would be free from all set of restrictions even on air, unless and until the animal shows weird behavior and of the size, the Air management would provide a separate cabin. And to very particular, only the emotional support animals of the kind dogs, cats, rabbits, parrots, to an extent are allowed, wherein a very few would love ESA of snakes, lizards and other set of reptiles, and those criteria require a high level certification.